The calculated distance (air line) between Birsfelden and Zürich (Kreis 6) is approximately 44 miles respectively 71 kilometers.
By car or train, the actual journey to Zürich (Kreis 6) is certainly longer, as only the direct route (as the crow flies) between Birsfelden and Zürich (Kreis 6) has been calculated here.
Air line (approximately)
71 kilometers
39 nautical miles